Is it essential to tell the suitor that she has had an ovary removed?
If what happened to you of having an ovary removed did not affect your ability to have children because the other ovary is working well, then you do not have to tell your suitor about that, because the definition of the kind of fault which must be disclosed is that which affects the marriage by causing an inability to provide physical pleasure or service or to bear children. But it is better to tell your suitor about it so as to prevent any problems later on if the husband were to regard not informing him about that as a kind of deception.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: The correct view is that what is regarded as a fault is anything which causes the aims of marriage not to be fulfilled. Undoubtedly the aims of marriage are physical pleasure, service and bearing children. These are the most important aims. If there is anything that prevents fulfilment of these aims, then it is a fault. Based on this, if the wife discovered that the husband is infertile or he discovers that she is infertile, this is a fault. If he finds out that she is blind, this is a fault, because this undermines two aims of marriage, namely physical pleasure and service; if he finds out that she is deaf, this is a fault; similarly, if he finds out that she is mute, this is a fault. The correct view is anything that undermines the aims of marriage is regarded as a fault where the option (of annulling the marriage) is given to either the husband or the wife. End quote from al-Sharh al-Mumti’ (12/220).
And Allaah knows best.